Re: [Intel-gfx] [PATCH] drm/vgem: Replace vgem_object_funcs with the common drm shmem helper

[Daniel Vetter <daniel@ffwll.ch>]

On Fri, Oct 9, 2020 at 12:21 PM Chris Wilson <chris@chris-wilson.co.uk> wrote:
>
> vgem is a minimalistic driver that provides shmemfs objects to
> userspace that may then be used as an in-memory surface and transported
> across dma-buf to other drivers. Since it's introduction,
> drm_gem_shmem_helper now provides the same shmemfs facilities and so we
> can trim vgem to wrap the helper.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/Kconfig         |   1 +
>  drivers/gpu/drm/vgem/vgem_drv.c | 281 ++------------------------------
>  drivers/gpu/drm/vgem/vgem_drv.h |  11 --
>  3 files changed, 13 insertions(+), 280 deletions(-)

Nice diffstat :-)

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

>
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index 147d61b9674e..db2ff76638cd 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -278,6 +278,7 @@ source "drivers/gpu/drm/i915/Kconfig"
>  config DRM_VGEM
>         tristate "Virtual GEM provider"
>         depends on DRM
> +       select DRM_GEM_SHMEM_HELPER
>         help
>           Choose this option to get a virtual graphics memory manager,
>           as used by Mesa's software renderer for enhanced performance.
> diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
> index fa54a6d1403d..73cb17c4f7a8 100644
> --- a/drivers/gpu/drm/vgem/vgem_drv.c
> +++ b/drivers/gpu/drm/vgem/vgem_drv.c
> @@ -38,6 +38,7 @@
>
>  #include <drm/drm_drv.h>
>  #include <drm/drm_file.h>
> +#include <drm/drm_gem_shmem_helper.h>
>  #include <drm/drm_ioctl.h>
>  #include <drm/drm_managed.h>
>  #include <drm/drm_prime.h>
> @@ -50,87 +51,11 @@
>  #define DRIVER_MAJOR   1
>  #define DRIVER_MINOR   0
>
> -static const struct drm_gem_object_funcs vgem_gem_object_funcs;
> -
>  static struct vgem_device {
>         struct drm_device drm;
>         struct platform_device *platform;
>  } *vgem_device;
>
> -static void vgem_gem_free_object(struct drm_gem_object *obj)
> -{
> -       struct drm_vgem_gem_object *vgem_obj = to_vgem_bo(obj);
> -
> -       kvfree(vgem_obj->pages);
> -       mutex_destroy(&vgem_obj->pages_lock);
> -
> -       if (obj->import_attach)
> -               drm_prime_gem_destroy(obj, vgem_obj->table);
> -
> -       drm_gem_object_release(obj);
> -       kfree(vgem_obj);
> -}
> -
> -static vm_fault_t vgem_gem_fault(struct vm_fault *vmf)
> -{
> -       struct vm_area_struct *vma = vmf->vma;
> -       struct drm_vgem_gem_object *obj = vma->vm_private_data;
> -       /* We don't use vmf->pgoff since that has the fake offset */
> -       unsigned long vaddr = vmf->address;
> -       vm_fault_t ret = VM_FAULT_SIGBUS;
> -       loff_t num_pages;
> -       pgoff_t page_offset;
> -       page_offset = (vaddr - vma->vm_start) >> PAGE_SHIFT;
> -
> -       num_pages = DIV_ROUND_UP(obj->base.size, PAGE_SIZE);
> -
> -       if (page_offset >= num_pages)
> -               return VM_FAULT_SIGBUS;
> -
> -       mutex_lock(&obj->pages_lock);
> -       if (obj->pages) {
> -               get_page(obj->pages[page_offset]);
> -               vmf->page = obj->pages[page_offset];
> -               ret = 0;
> -       }
> -       mutex_unlock(&obj->pages_lock);
> -       if (ret) {
> -               struct page *page;
> -
> -               page = shmem_read_mapping_page(
> -                                       file_inode(obj->base.filp)->i_mapping,
> -                                       page_offset);
> -               if (!IS_ERR(page)) {
> -                       vmf->page = page;
> -                       ret = 0;
> -               } else switch (PTR_ERR(page)) {
> -                       case -ENOSPC:
> -                       case -ENOMEM:
> -                               ret = VM_FAULT_OOM;
> -                               break;
> -                       case -EBUSY:
> -                               ret = VM_FAULT_RETRY;
> -                               break;
> -                       case -EFAULT:
> -                       case -EINVAL:
> -                               ret = VM_FAULT_SIGBUS;
> -                               break;
> -                       default:
> -                               WARN_ON(PTR_ERR(page));
> -                               ret = VM_FAULT_SIGBUS;
> -                               break;
> -               }
> -
> -       }
> -       return ret;
> -}
> -
> -static const struct vm_operations_struct vgem_gem_vm_ops = {
> -       .fault = vgem_gem_fault,
> -       .open = drm_gem_vm_open,
> -       .close = drm_gem_vm_close,
> -};
> -
>  static int vgem_open(struct drm_device *dev, struct drm_file *file)
>  {
>         struct vgem_file *vfile;
> @@ -159,41 +84,25 @@ static void vgem_postclose(struct drm_device *dev, struct drm_file *file)
>         kfree(vfile);
>  }
>
> -static struct drm_vgem_gem_object *__vgem_gem_create(struct drm_device *dev,
> +static struct drm_gem_shmem_object *__vgem_gem_create(struct drm_device *dev,
>                                                 unsigned long size)
>  {
> -       struct drm_vgem_gem_object *obj;
> -       int ret;
> -
> -       obj = kzalloc(sizeof(*obj), GFP_KERNEL);
> -       if (!obj)
> -               return ERR_PTR(-ENOMEM);
> +       struct drm_gem_shmem_object *obj;
>
> -       obj->base.funcs = &vgem_gem_object_funcs;
> -
> -       ret = drm_gem_object_init(dev, &obj->base, roundup(size, PAGE_SIZE));
> -       if (ret) {
> -               kfree(obj);
> -               return ERR_PTR(ret);
> -       }
> -
> -       mutex_init(&obj->pages_lock);
> +       obj = drm_gem_shmem_create(dev, round_up(size, PAGE_SIZE));
> +       if (IS_ERR(obj))
> +               return obj;
>
> +       obj->map_cached = true;
>         return obj;
>  }
>
> -static void __vgem_gem_destroy(struct drm_vgem_gem_object *obj)
> -{
> -       drm_gem_object_release(&obj->base);
> -       kfree(obj);
> -}
> -
>  static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
>                                               struct drm_file *file,
>                                               unsigned int *handle,
>                                               unsigned long size)
>  {
> -       struct drm_vgem_gem_object *obj;
> +       struct drm_gem_shmem_object *obj;
>         int ret;
>
>         obj = __vgem_gem_create(dev, size);
> @@ -239,96 +148,9 @@ static struct drm_ioctl_desc vgem_ioctls[] = {
>         DRM_IOCTL_DEF_DRV(VGEM_FENCE_SIGNAL, vgem_fence_signal_ioctl, DRM_RENDER_ALLOW),
>  };
>
> -static int vgem_mmap(struct file *filp, struct vm_area_struct *vma)
> -{
> -       unsigned long flags = vma->vm_flags;
> -       int ret;
> -
> -       ret = drm_gem_mmap(filp, vma);
> -       if (ret)
> -               return ret;
> -
> -       /* Keep the WC mmaping set by drm_gem_mmap() but our pages
> -        * are ordinary and not special.
> -        */
> -       vma->vm_flags = flags | VM_DONTEXPAND | VM_DONTDUMP;
> -       return 0;
> -}
> -
> -static const struct file_operations vgem_driver_fops = {
> -       .owner          = THIS_MODULE,
> -       .open           = drm_open,
> -       .mmap           = vgem_mmap,
> -       .poll           = drm_poll,
> -       .read           = drm_read,
> -       .unlocked_ioctl = drm_ioctl,
> -       .compat_ioctl   = drm_compat_ioctl,
> -       .release        = drm_release,
> -};
> -
> -static struct page **vgem_pin_pages(struct drm_vgem_gem_object *bo)
> -{
> -       mutex_lock(&bo->pages_lock);
> -       if (bo->pages_pin_count++ == 0) {
> -               struct page **pages;
> -
> -               pages = drm_gem_get_pages(&bo->base);
> -               if (IS_ERR(pages)) {
> -                       bo->pages_pin_count--;
> -                       mutex_unlock(&bo->pages_lock);
> -                       return pages;
> -               }
> -
> -               bo->pages = pages;
> -       }
> -       mutex_unlock(&bo->pages_lock);
> -
> -       return bo->pages;
> -}
> -
> -static void vgem_unpin_pages(struct drm_vgem_gem_object *bo)
> -{
> -       mutex_lock(&bo->pages_lock);
> -       if (--bo->pages_pin_count == 0) {
> -               drm_gem_put_pages(&bo->base, bo->pages, true, true);
> -               bo->pages = NULL;
> -       }
> -       mutex_unlock(&bo->pages_lock);
> -}
> -
> -static int vgem_prime_pin(struct drm_gem_object *obj)
> -{
> -       struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
> -       long n_pages = obj->size >> PAGE_SHIFT;
> -       struct page **pages;
> +DEFINE_DRM_GEM_FOPS(vgem_driver_fops);
>
> -       pages = vgem_pin_pages(bo);
> -       if (IS_ERR(pages))
> -               return PTR_ERR(pages);
> -
> -       /* Flush the object from the CPU cache so that importers can rely
> -        * on coherent indirect access via the exported dma-address.
> -        */
> -       drm_clflush_pages(pages, n_pages);
> -
> -       return 0;
> -}
> -
> -static void vgem_prime_unpin(struct drm_gem_object *obj)
> -{
> -       struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
> -
> -       vgem_unpin_pages(bo);
> -}
> -
> -static struct sg_table *vgem_prime_get_sg_table(struct drm_gem_object *obj)
> -{
> -       struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
> -
> -       return drm_prime_pages_to_sg(obj->dev, bo->pages, bo->base.size >> PAGE_SHIFT);
> -}
> -
> -static struct drm_gem_object* vgem_prime_import(struct drm_device *dev,
> +static struct drm_gem_object *vgem_prime_import(struct drm_device *dev,
>                                                 struct dma_buf *dma_buf)
>  {
>         struct vgem_device *vgem = container_of(dev, typeof(*vgem), drm);
> @@ -336,85 +158,6 @@ static struct drm_gem_object* vgem_prime_import(struct drm_device *dev,
>         return drm_gem_prime_import_dev(dev, dma_buf, &vgem->platform->dev);
>  }
>
> -static struct drm_gem_object *vgem_prime_import_sg_table(struct drm_device *dev,
> -                       struct dma_buf_attachment *attach, struct sg_table *sg)
> -{
> -       struct drm_vgem_gem_object *obj;
> -       int npages;
> -
> -       obj = __vgem_gem_create(dev, attach->dmabuf->size);
> -       if (IS_ERR(obj))
> -               return ERR_CAST(obj);
> -
> -       npages = PAGE_ALIGN(attach->dmabuf->size) / PAGE_SIZE;
> -
> -       obj->table = sg;
> -       obj->pages = kvmalloc_array(npages, sizeof(struct page *), GFP_KERNEL);
> -       if (!obj->pages) {
> -               __vgem_gem_destroy(obj);
> -               return ERR_PTR(-ENOMEM);
> -       }
> -
> -       obj->pages_pin_count++; /* perma-pinned */
> -       drm_prime_sg_to_page_addr_arrays(obj->table, obj->pages, NULL,
> -                                       npages);
> -       return &obj->base;
> -}
> -
> -static void *vgem_prime_vmap(struct drm_gem_object *obj)
> -{
> -       struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
> -       long n_pages = obj->size >> PAGE_SHIFT;
> -       struct page **pages;
> -
> -       pages = vgem_pin_pages(bo);
> -       if (IS_ERR(pages))
> -               return NULL;
> -
> -       return vmap(pages, n_pages, 0, pgprot_writecombine(PAGE_KERNEL));
> -}
> -
> -static void vgem_prime_vunmap(struct drm_gem_object *obj, void *vaddr)
> -{
> -       struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
> -
> -       vunmap(vaddr);
> -       vgem_unpin_pages(bo);
> -}
> -
> -static int vgem_prime_mmap(struct drm_gem_object *obj,
> -                          struct vm_area_struct *vma)
> -{
> -       int ret;
> -
> -       if (obj->size < vma->vm_end - vma->vm_start)
> -               return -EINVAL;
> -
> -       if (!obj->filp)
> -               return -ENODEV;
> -
> -       ret = call_mmap(obj->filp, vma);
> -       if (ret)
> -               return ret;
> -
> -       fput(vma->vm_file);
> -       vma->vm_file = get_file(obj->filp);
> -       vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
> -       vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
> -
> -       return 0;
> -}
> -
> -static const struct drm_gem_object_funcs vgem_gem_object_funcs = {
> -       .free = vgem_gem_free_object,
> -       .pin = vgem_prime_pin,
> -       .unpin = vgem_prime_unpin,
> -       .get_sg_table = vgem_prime_get_sg_table,
> -       .vmap = vgem_prime_vmap,
> -       .vunmap = vgem_prime_vunmap,
> -       .vm_ops = &vgem_gem_vm_ops,
> -};
> -
>  static struct drm_driver vgem_driver = {
>         .driver_features                = DRIVER_GEM | DRIVER_RENDER,
>         .open                           = vgem_open,
> @@ -428,8 +171,8 @@ static struct drm_driver vgem_driver = {
>         .prime_handle_to_fd = drm_gem_prime_handle_to_fd,
>         .prime_fd_to_handle = drm_gem_prime_fd_to_handle,
>         .gem_prime_import = vgem_prime_import,
> -       .gem_prime_import_sg_table = vgem_prime_import_sg_table,
> -       .gem_prime_mmap = vgem_prime_mmap,
> +       .gem_prime_import_sg_table = drm_gem_shmem_prime_import_sg_table,
> +       .gem_prime_mmap = drm_gem_prime_mmap,
>
>         .name   = DRIVER_NAME,
>         .desc   = DRIVER_DESC,
> diff --git a/drivers/gpu/drm/vgem/vgem_drv.h b/drivers/gpu/drm/vgem/vgem_drv.h
> index 0ed300317f87..34cf63e6fb3d 100644
> --- a/drivers/gpu/drm/vgem/vgem_drv.h
> +++ b/drivers/gpu/drm/vgem/vgem_drv.h
> @@ -39,17 +39,6 @@ struct vgem_file {
>         struct mutex fence_mutex;
>  };
>
> -#define to_vgem_bo(x) container_of(x, struct drm_vgem_gem_object, base)
> -struct drm_vgem_gem_object {
> -       struct drm_gem_object base;
> -
> -       struct page **pages;
> -       unsigned int pages_pin_count;
> -       struct mutex pages_lock;
> -
> -       struct sg_table *table;
> -};
> -
>  int vgem_fence_open(struct vgem_file *file);
>  int vgem_fence_attach_ioctl(struct drm_device *dev,
>                             void *data,
> --
> 2.20.1
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx



-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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